Devices generating synchronizing signals in sewing machines

Abstract

A sewing machine (100) having a needle bar (120,122) and feed means (131,132,602,603) in which actuators (124,130) adjust the transverse position of the needle bar (120,122) and the positional displacement of the feed means (131,132,602,603) in response to control signals provided thereto, and a rotatable main shaft (104,204,205) operatively connected to the needle bar (120,122) for enabling transverse oscillation thereof which shaft (104) is driven by a main motor (201), includes an arrangement for generating synchronizing timing control signals to the actuators (124,130) and a stop control signal to the motor (201) to stop the shaft (104,204,205) in a predetermined arc of rotation in which a common magnet (208,508) mounted in a holder (207,507) for rotation with the shaft (104,204,205) interacts with a pair of spaced apart magnistors (211,213) to provide the timing control signals to the actuators (124,130) and a separate magnet means which may be either a single magnet (509) or a pair of spaced apart magnets (209,210 ), also mounted in the holder (207,507) interacts with a separate magnistor (212) to provide the stop control signal. The magnistors (211,212,213) are linearly arranged on a printed circuit board (313) forming part of the machine circuitry. A soft iron loop (601) may be provided to surround the area of such interaction so as to close the magnetic path and increase the associated flux density and minimize losses.

What is claimed is: 
     
       1. In a sewing machine having a needle bar means capable of transverse oscillation thereof relative to the direction of fabric feed in said sewing machine, feed means for adjusting the length and direction of said fabric feed, first actuator means for adjusting the transverse position of said needle bar means in response to control signals provided thereto, second actuator means for adjusting the positional displacement of said feed means in response to control signals provided thereto, rotatable main shaft means operatively connected to said needle bar means for enabling said transverse oscillation thereof, and main drive motor means drivingly connected to said main shaft means and said feed means for enabling sewing by said sewing machine; the improvement comprising means for generating synchronizing timing control signals to at least said first and second actuator means, said generating means comprising a first magnetic sensor means associated with said first actuator means and a second magnetic sensor means associated with said second actuator means and spaced from said first sensor means, and a first common magnet means disposed for synchronous rotation with said main shaft means for successively interacting with said first and second magnetic sensor means during rotation of said main shaft means for successively providing said synchronizing timing control signals. 
     
     
       2. An improved sewing machine in accordance with claim 1 wherein said generating means further comprises a second magnet means disposed for synchronous rotation with said main shaft means and a third magnetic sensor means associated with said main drive motor means for providing a stop control synchronizing signal thereto, said second magnetic means being disposed for interacting with said third magnetic sensor means for a sufficient angular interval of rotation of said main shaft means to enable stopping of said main shaft means in a predetermined arc of rotation of said main shaft means. 
     
     
       3. An improved sewing machine in accordance with claim 2 wherein said first and second magnet means are mounted on said main shaft means for rotation therewith. 
     
     
       4. An improved sewing machine in accordance with claim 3 wherein said first and second magnet means are mounted on said main shaft means in a common holder therefor. 
     
     
       5. An improved sewing machine in accordance with claim 4 wherein said first and second magnet means comprise permanent magnets. 
     
     
       6. An improved sewing machine in accordance with claim 5 wherein said second magnet means comprises a pair of magnets angularly spaced apart from each other in the direction of rotation of said main shaft means by substantially said predetermined arc of rotation. 
     
     
       7. An improved sewing machine in accordance with claim 6 wherein said predetermined arc of rotation is substantially about 50 degrees. 
     
     
       8. An improved sewing machine in accordance with claim 7 wherein said first and second magnetic sensor means are linearly spaced apart from each other in a common plane, with said linear spacing being defined by a predetermined angular rotation of said first common magnet means sufficient for providing a predetermined interval between said successive interaction for successively providing said synchronizing timing control signals. 
     
     
       9. An improved sewing machine in accordance with claim 8 wherein said angular rotation is substantially about 175 degrees. 
     
     
       10. An improved sewing machine in accordance with claim 9 wherein said third magnetic sensor means is linearly spaced apart from said first and second magnetic sensor means in said common plane. 
     
     
       11. An improved sewing machine in accordance with claim 10 wherein said first, second and third magnetic sensor means comprise Hall-effect type sensors. 
     
     
       12. An improved sewing machine in accordance with claim 11 wherein said first magnet means is mounted on said main shaft means for rotation therewith. 
     
     
       13. An improved sewing machine in accordance with claim 12 wherein said first magnet means comprises a permanent magnet. 
     
     
       14. An improved sewing machine in accordance with claim 13 wherein said first and second magnetic sensor means comprise Hall-effect type sensors. 
     
     
       15. An improved sewing machine in accordance with claim 1 wherein said first and second magnetic sensor means are linearly spaced apart from each other in a common plane, with said linear spacing being defined by a predetermined angular rotation of said first common magnet means sufficient for providing a predetermined interval between said successive interaction for successively providing said synchronizing timing control signals. 
     
     
       16. An improved sewing machine in accordance with claim 15 wherein said angular rotatin is substantially about 175 degrees. 
     
     
       17. An improved sewing machine in accordance with claim 15 wherein said first magnet means comprises a permanent magnet. 
     
     
       18. An improved sewing machine in accordance with claim 17 wherein said first and second magnetic sensor means comprise Hall-effect type sensors. 
     
     
       19. An improved sewing machine in accordance with claim 2 wherein said second magnet means comprises a pair of magnets angularly spaced apart from each other in the direction of rotation of said main shaft means by substantially said predetermined arc of rotation. 
     
     
       20. An improved sewing machine in accordance with claim 19 wherein said predetermined arc of rotation is substantially about 50 degrees. 
     
     
       21. An improved sewing machine in accordance with claim 2 wherein said first and second magnetic sensor means are linearly spaced apart from each other in a common plane, with said linear spacing being defined by a predetermined angular rotation of said first common magnet means sufficient for providing a predetermined interval between said successive interaction for successively providing said synchronizing timing control signals. 
     
     
       22. An improved sewing machine in accordance with claim 21 wherein said angular rotation is substantially about 175 degrees. 
     
     
       23. An improved sewing machine in accordance with claim 21 wherein said third magnetic sensor means is linearly spaced apart from said first and second magnetic sensor means in said common plane. 
     
     
       24. An improved sewing machine in accordance with claim 23 wherein said first and second magnet means comprise permanent magnets. 
     
     
       25. An improved sewing machine in accordance with claim 24 wherein said first, second and third magnetic sensor means comprise Hall-effect type sensors. 
     
     
       26. An improved sewing machine in accordance with claim 1 wherein said first common magnet means successively interacts with said first and second magnetic sensor means at the beginning of upper exit of the needle from the fabric and the beginning of lower entrance of the needle into the fabric, respectively, during the rotation of said main shaft means. 
     
     
       27. An improved sewing machine in accordance with claim 2 wherein said second magnet means interacts with said third magnetic sensor means substantially in the maximum upper exit condition of the needle from the fabric during the rotation of said main shaft means. 
     
     
       28. An improved sewing machine in accordance with claim 23 wherein said common plane is defined by a printed circuit board comprising associated circuitry for said sewing machine. 
     
     
       29. An improved sewing machine in accordance with claim 28 wherein said sewing machine further comprises a keyboard, said keyboard and said printed circuit board being mountable in said sewing machine in a common housing therefor. 
     
     
       30. An improved sewing machine in accordance with claim 4 wherein said common holder comprises a resilient member having a bifurcated portion for facilitating mounting thereof on said main shaft means. 
     
     
       31. An improved sewing machine in accordance with claim 1 wherein said generating means further comprises a soft iron loop substantially surrounding the area of interaction of said first magnet means and said first and second magnetic sensor means for facilitating closure of the magnetic path formed in said area and increasing the associated flux density within said area. 
     
     
       32. An improved sewing machine in accordance with claim 2 wherein said generating means further comprises a soft iron loop substantially surrounding the area of interaction of said first magnet means and said first and second magnetic sensor means and said second magnet means and said third magnetic sensor means for facilitating closure of the magnetic path formed in said area and increasing the associated flux density within said area. 
     
     
       33. An improved sewing machine in accordance with claim 3 wherein said first and second magnet means are angularly spaced apart by substantially 90 degrees in the direction of rotation of said main shaft means. 
     
     
       34. An improved sewing machine in accordance with claim 33 wherein said first and second magnet means are mounted on said main shaft means in a common holder therefor. 
     
     
       35. An improved sewing machine in accordance with claim 33 wherein said second magnet means comprises a pair of magnets angularly spaced apart from each other in the direction of rotation of said main shaft means by substantially said predetermined arc of rotation, said first magnet means being angularly spaced apart by substantially 90 degrees from a point intermediate the angular spacing between said pair of magnets comprising said second magnet means. 
     
     
       36. An improved sewing machine in accordance with claim 2 wherein said second magnet means comprises a single magnet having a sufficient angular extent between the extremities thereof defined by said predetermined arc of rotation. 
     
     
       37. An improved sewing machine in accordance with claim 1 wherein said first and second magnetic sensor means comprise magnistors. 
     
     
       38. An improved sewing machine in accordance with claim 37 wherein said third magnetic sensor means comprises a magnistor. 
     
     
       39. In a sewing machine having a needle bar means capable of transverse oscillation thereof relative to the direction of fabric feed in said sewing machine, feed means for adjusting the length and direction of said fabric feed, first actuator means for adjusting the transverse position of said needle bar means in response to control signals provided thereto, second actuator means for adjusting the positional displacement of said feed means in response to control signals provided thereto, rotatable main shaft means operatively connected to said needle bar means for enabling said transverse oscillation thereof, and main drive motor means drivingly connected to said main shaft means and said feed means for enabling sewing by said sewing machine; the improvement comprising means for generating a stop control synchronizing signal to said main drive motor means, said generating means comprising a first magnetic sensor means associated with said main drive motor means for providing said stop control synchronizing signal thereto, and a first magnet means disposed for synchronous rotation with said main shaft means for interacting with said first magnetic sensor means for a sufficient angular interval of rotation to enable stopping of said main shaft means in a predetermined arc of rotation of said main shaft means, said first magnet means comprising a pair of magnets angularly spaced apart from each other in the direction of rotation of said main shaft means by substantially said predetermined arc of rotation. 
     
     
       40. An improved sewing machine in accordance with claim 39 wherein said predetermined arc of rotation is substantially about 50 degrees. 
     
     
       41. In a sewing machine having a needle bar means capable of transverse oscillation thereof relative to the direction of fabric feed in said sewing machine, feed means for adjusting the length and direction of said fabric feed, first actuator means for adjusting the transverse position of said needle bar means in response to control signals provided thereto, second actuator means for adjusting the positional displacement of said feed means in response to control signals provided thereto, rotatable main shaft means operatively connected to said needle bar means for enabling said transverse oscillation thereof, and main drive motor means drivingly connected to said main shaft means and said feed means for enabling sewing by said sewing machine; the improvement comprising means for generating a stop control synchronizing signal to said main drive motor means, said generating means comprising a first magnetic sensor means associated with said main drive motor means for providing said stop control synchronizing signal thereto, and a first magnet means disposed for synchronous rotation with said main shaft means for interacting with said first magnetic sensor means for a sufficient angular interval of rotation to enable stopping of said main shaft means in a predetermined arc of rotation of said main shaft means, wherein said generating means further comprises a soft iron loop substantially surrounding the area of interaction of said first magnet means and said first magnetic sensor means for facilitating closure of the magnetic path formed in said area and increasing the associated flux density within said area.